Ok so my seats are both very good, not a single rip.

Drivers seat flexes, I am told the fiberglass is cracked where the back meets the bottom and that it is "common".

Is there a way to fix this? I hate to throw baby out with the bath water so to speak.

Anyone fixed the fiberglass without pulling the 30 year old cover off?

i had a similar feeling. the seat had unbolted from the rail. pull the seat and make sure 4 screws on each side are there

Have you pulled the lower cushion out to see if you can find any damage to the FG shell?